Hamideh Abbasi; Ghodrat Torabi
Volume 4, Issue 13 , April 2013, , Pages 19-32
Abstract
Ku-e-Kam Khashak is located in the NE of Isfahan (North of Khur). Basic dykes trending NE-SW and intermediate dykes with NW-SE trend cross cut the Upper Cretaceous sandstone, limestone ...
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Ku-e-Kam Khashak is located in the NE of Isfahan (North of Khur). Basic dykes trending NE-SW and intermediate dykes with NW-SE trend cross cut the Upper Cretaceous sandstone, limestone and marl. The intermediate dykes are much more abundant and widespread in the area. Field studies show that the basic dykes cross-cutting the intermediate dykes, indicating that intermediate dykes are older. Primary minerals of the basic dykes are olivine (chrysolite), clinopyroxene (diopside, augite), plagioclase (labradorite, oligoclase), sanidine, magnetite, orthopyroxene (enstatite), spinel, phlogopite and secondary minerals are zeolite (natrolite and mesolite), chlorite, calcite and serpentine. The intermediate dykes are composed of clinopyroxene (diopside), plagioclase (labradorite), sanidine, mica (biotite and phlogopite), amphibole (magnesio-hastingsite) and magnetite as primary minerals and chlorite and calcite as secondary minerals. Basic dykes have xenocrysts of quartz and xenoliths with pyroxenite and hornfels in composition. Mineral chemistry of clinopyroxenes reveals pressure less than 5 kbars and variable PH2O for the formation of these phases. Thermometry of the micas in intermediate dykes show 732- 747 °C, whereas the biotites of basic dykes crystallized 699 to 808 °C. Petrography and mineral chemistry of the studied dykes indicate sub- alkaline and calc- alkaline characteristic of the primary magma and their magmatic arc setting.
